DC to DC charger

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DC to DC charger

Postby RTD » Thu Jun 08, 2017 4:56 pm

I have been reading about charging my teardrop battery from my tow vehicle, and they say it doesn't put out enough volts to fully charge the teardrops battery. I just ordered a 125 a/h Lifeline battery which will work in my battery box. What I need is a DC to DC charger (they say). Does anyone know about this and what is a good one to purchase?
Thanks for any advice.
Nearly done with my build, only took 3 years.
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Re: DC to DC charger

Postby lrrowe » Thu Jun 08, 2017 5:08 pm

Bob

First Post on Purchase of Trailer: http://www.tnttt.com/viewtopic.php?f=42&t=60722
Hot water infloor and radiator heating project:[url]http://www.tnttt.com/posting.php?mode=reply&f=54&t=62327[/

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Re: DC to DC charger

Postby RTD » Fri Jun 09, 2017 8:04 pm

Thanks for the info, will do more research.
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Re: DC to DC charger

Postby tony.latham » Fri Jun 09, 2017 11:31 pm

and they say it doesn't put out enough volts to fully charge the teardrops battery.


I don't know where you read that. I suppose it may have some arguable validity. My current battery is a Group 27 Marine battery purchased four years ago. It gets charged while driving and when we arrive, it appears to be fully charged (based on resting voltage). It also seems to be as healthy now as when I bought it.

Tony
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Re: DC to DC charger

Postby H.A. » Fri Jun 09, 2017 11:55 pm

Mk it.
Last edited by H.A. on Thu Jul 06, 2017 4:04 am, edited 1 time in total.
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Re: DC to DC charger

Postby Dale M. » Sat Jun 10, 2017 7:17 am

IF you drive 100 miles on next trip and stop and put volt meter across the tow vehicle battery and take a reading, and if you disconnect the"charge while towing" and go to trailer battery and take a reading and if there is less than one half a volt (.5 Volt) difference, battery in trailer is being sufficient charged... If not within parameters your vehicle wiring or trailer wiring is not up to task and you just need to replace it with heavier wire gauge or trailer battery in trailer is on its way out.... Batteries in parallel should read same voltages...

Or when in drive way have some lightly depress gas pedal to rev engine up to maybe 2000rpm and measure battery voltage across tow vehicle battery... With engine still "revving" measure trailer battery, reading should be same... If the are the same you do not have problem, if trailer battery is less , then your vehicle wiring is not up to the job and you are getting voltage loss in vehicles (TV + trailer) charging wiring...

IF you are getting anywhere from 13.8 to 14.5 volts at trailer battery DC to DC charger is not needed..

For the most part buying a expensive DC to DC charger is only going to drain wallet and not improve battery life...

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Re: DC to DC charger

Postby RTD » Sat Jun 10, 2017 12:58 pm

Thanks again for the info. When I get my battery and wire it up, I'll check the voltage at the teardrop to see if I need a DC to DC charger.
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Re: DC to DC charger

Postby GuitarPhotog » Sat Jun 10, 2017 5:24 pm

RTD wrote:I have been reading about charging my teardrop battery from my tow vehicle, and they say it doesn't put out enough volts to fully charge the teardrops battery. I just ordered a 125 a/h Lifeline battery which will work in my battery box. What I need is a DC to DC charger (they say). Does anyone know about this and what is a good one to purchase?
Thanks for any advice.
Nearly done with my build, only took 3 years.


Another data point.

I have been charging my 60AH AGM battery from the tow vehicle for 4 of the 6 years I've had the trailer. The battery is always fully charged when I arrive at my destination (I never discharge below 60%). On days I'm not towing the trailer, I have an 80W solar panel and charge controller to charge the battery.

<Chas>
:beer:
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Re: DC to DC charger

Postby daveesl77 » Wed Jun 21, 2017 7:52 am

When driving we charge the camper battery from the tow vehicle, whether the previous F150 which had the built in, auto-disconnect charge line or the minivan with the switched charge line I made. We charge while driving because we run the dorm fridge from the inverter. This keeps the dorm fridge running really well, while at the same time keeping the battery charged. I did build an isolator circuit too.

As to wiring, from fuseblock from battery to van side trailer plug, I ran 8 gauged wire, with 20 amp fuse. On camper side, same #8 wire to switch, through isolator, to battery. I considered using one of my two, 50 amp, digital relays I've had for years, but just could not bring myself to use it for something this simple. Yes, I've been saying the same thing on every project for about 10 years now. :D Sooner or later I will use them on something (or not).

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Re: DC to DC charger

Postby Trebor English » Wed Jun 21, 2017 11:07 am

Do you have an inverter? Do you have a battery charger? Do like the power company and use a high voltage transmission line. Have a place near the tow vehicle alternator for the inverter and run a 120 volt extension cord to the battery charger in the tnttt. When you get where you are going move the inverter (or have two). With the current reduced to one tenth you could use 14 or 16 instead of 8 gauge wire. Putting the charger regulator at the battery makes the voltage be what the battery needs not just what's left over. The distance from the front of the tow vehicle to the back of the trailer matters much less.
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Re: DC to DC charger

Postby nemoskull » Tue Jun 27, 2017 4:45 pm

ebay has some 3 amp 15 volt laptop chargers i was looking at for shore power. paralleling serveral of them would require some cureent limiting resistors tho. they were cheap, and running them directly into a PWM solar charger would make it close to 90% effiecnt.
just my .02
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